It looks like you're not using I's and 0's (eyes and zeros :) ) but removing all the possible glyph confusions will probably help reduce errors, and it doesn't cost you that much of the space.

I just read the "About Couponcode" tab - the autocorrect is a very nice feature, but it might be worth mentioning that feature on the front page, so the customer doesn't worry while reading the code...

Thanks - I've added a mention of the auto-correction on the front page of the demo.

In a real application I'm not sure that I'd bother mentioning it. It would be nice if there was some easy way to reassure people that they didn't need to stress about upper/lower case and whether it's a '0' or an 'O' but that would take words and people don't read words.

When putting a smiley right before a closing parenthesis, do you:

Use two parentheses: (Like this: :) )
Use one parenthesis: (Like this: :)
Reverse direction of the smiley: (Like this: (: )
Use angle/square brackets instead of parentheses
Use C-style commenting to set the smiley off from the closing parenthesis
Make the smiley a dunce: (:>
I disapprove of emoticons
Other